Claude Code + Telnyx: build and test a phone agent

Prepare the agent’s job and connection

Thanks to Telnyx for sponsoring this video.

The walkthrough builds a hosted voice agent with order lookup and guardrails. Telnyx provides the voice/telephony route; the original repository contains the exact demonstrated master prompt.

1. Open the team-telnyx/ai repository retained with this video.
2. Define the allowed answers, lookup inputs and boundaries for your own demo.
3. Follow the recorded plugin and API-key setup, keeping the key out of shared files and chat.
4. Review the master prompt before it creates or changes account resources.

Inspect the assistant before attaching live callers

The recording includes automated checks of answers, boundaries and closing behaviour. A plausible greeting alone is not a complete test.

1. Check the configured voice, model, greeting, instructions and knowledge.
2. Test a normal lookup, missing information and an out-of-scope request using demo data.
3. Inspect the actual responses and revise a specific failure.
4. Check what the assistant does when it cannot safely complete the request.

Test the phone route and running cost

The video adds a UK or US number and places a real test call. Current number availability and usage prices must be checked at the destination.

1. Use the demonstrated number-assignment route for the approved test setup.
2. Call the number yourself and complete the same test cases used earlier.
3. Inspect the closing behaviour and the resulting call records.
4. Review number and call usage charges separately before putting customer traffic through the agent.

The takeaway

A connected number is only one part of the result. Verify the answers, handoffs and account usage before relying on the service.